1. Field of the Invention
The present invention generally relates to controlling an air conditioner to manage the thermal effect of the condenser preheating air that is used to cool the engine or other components of the vehicle. In other words, the present invention relates to control of an air conditioner such that the performance of the air conditioner is reduced in response to increases in the thermal condition of the engine or other components of the vehicle affected by the condenser temperature.
2. Background Information
A typical automobile air conditioner includes a compressor, a condenser, an expansion valve or orifice tube, and an evaporator. The compressor compresses a cool vapor-phase refrigerant (e.g., Freon, R134a) to heat the same, resulting in a hot, high-pressure vapor-phase refrigerant. This hot vapor-phase refrigerant runs through a condenser, typically a coil that dissipates heat. The condenser condenses the hot vapor-phase refrigerant into liquid refrigerant. The liquid refrigerant is throttled through an expansion valve, which evaporates the refrigerant to a cold, low-pressure saturated liquid-vapor-phase refrigerant. This cold saturated liquid-vapor-phase refrigerant runs through the evaporator, typically a coil that absorbs heat from the air fed to the passenger compartment.
The condenser of the automobile air conditioner is typically located in front of the radiator of the automobile such that the air conditioner's condenser is essentially preheats the outside air that is used to cool the engine. Normally, this arrangement does not significantly effect the operation of the engine. However, during high ambient temperatures and high load conditions (e.g., hill climbing, towing, etc.), the engine temperature may rise above the suitable temperature ranges for the fluids and/or materials of the engine. In some conventional air conditioning systems, the engine controller will operate the air conditioner using normal control logic without regard to the thermal conditions of the engine and/or other components. However, when the engine control unit in these conventional air conditioning units determine that the thermal conditions of the engine and/or other components are very severe, then the engine controller completely turns off the air conditioner until the thermal conditions have returned to suitable level. Since the engine overheating normally occurs during high ambient temperatures, the vehicle cabin temperature often rises to uncomfortable levels when the air conditioner is shut off to allow the thermal conditions of the engine to return to suitable level.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved air conditioner control system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.